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The Magellan Mission
to Venus

The Magellan spacecraft, named after
the sixteenth-century Portuguese explorer whose
expedition first circumnavigated the Earth, was launched
May 4, 1989, and arrived at Venus on August 10, 1990.
During the first 8-month mapping cycle around Venus,
Magellan collected radar images of 84 percent of the
planet's surface, with resolution 10 times better than
that of the earlier Soviet Venera 15 and 16 missions.
Altimetry and radiometry data also measured the surface
topography and electrical characteristics. During the
extended mission, two further mapping cycles from May
15, 1991 to September 14, 1992 brought mapping coverage
to 98% of the planet, with a resolution of approximately
100m. Precision radio tracking of the spacecraft
measured Venus' gravitational field to show the planet's
internal mass distribution and the forces that have
created the surface features. Magellan's data permitted
the first global geological understanding of Venus, the
planet most like Earth in our solar system.

The ALTEDR volumes contain
Magellan ALT-EDR (Altimeter Experiment Data
Record) archive products. They also contain
documentation files which describe the ALT-EDRs.
Each ALT-EDR data directory contains the raw
altimeter data returned from one orbit and the
ancillary files necessary to understand the data.

The Surface Characteristics
Vector Data Record (SCVDR) is an orbit-by-orbit
reduction of Magellan scattering and emission
measurements carried out at Stanford University.
The SCVDR includes near-nadir scattering functions
obtained by numerical inversion from altimetry
(ALT) echoes, results (e.g., rms surface slopes
and Fresnel reflectivity) from fitting analytic
functions to those inversions, scattering function
segments at oblique incidence angles derived from
synthetic aperture radar (SAR) echoes, and
estimates of surface emissivity derived from
thermal microwave radiometry (RAD) measurements.
The SCVDR is one of several inputs to the Global
Vector Data Record (GVDR), a gridded summary of
scattering results, also produced at Stanford.

The Global Vector Data Record (GVDR)
is a sorted collection of scattering and emission
measurements. The sorting is into a grid of equal
area 'pixels' distributed regularly about the
planet. For data acquired from the same pixel but
in different observing geometries, there is a
second level of sorting to accommodate the
different geometrical conditions. The 'pixel'
dimension is 18.225 km. The GVDR is presented in
Sinusoidal Equal Area (equatorial), Mercator
(equatorial), and Polar Stereographic (polar)
projections.

This archive contains Magellan
Cycle 4, 5 and 6 LOSAPDR (Line of Sight
Acceleration Profile Data Record) products. It
also contains documentation which describes the
LOSAPDRs. Each LOSAPDR product contains the
results from processing of radio tracking data of
the Magellan spacecraft.

This archive was produced by the U.S. Geological Survey
after the Magellan mission ended. It contains
full-resolution mosaicked images covering about 92%
of the planet. Images were generated from the F-BIDR
products. This link leads to the PDS Imaging Node
web site.